Process of dyeing animal fibers



Patented Oct. 6, 19 42 A PROCESS OF DYEING ANIMAL FIBERS GustaveTheodore Hug, Penna Grove, N. 1., signer to E. I. du Pont de Nemours' aCom-- pany, Wilmington, Del, a corporation of Delaware \ No Drawing.Application April 11, 1940, Serial No. 329,108 I v Claims. (01. He)

. methods, thematerial may be dyed in a reduced This invention relatesto the dyeing of animal ilbers withindigoid and anthraguinone types ofvat'colors and more particularly to the pretreatment of wool to increaseits aflinity for indigo and other vat dyes.

This invention hasv as an object the dyeing of woolen piece goodscontinuously with vat dyes. A further object is the dyeing of animalfibers'in the form of piece goods, skeins or raw stock with indigoid andanthraquinone vat dyes. Other and further important objects of thisinvention will i appear as the description proceeds. J

, These objects are accomplished by the following invention whichconsists of p'retreating the woolen material by padding it through asolution or suspension of a sulfur-containing vat-reducing agent, forinstance a compound selected from the group consisting of formamidinesulflnic acid, hydrosulflte, the aldehyde sulfoxylates, thebisulfltesand the water-soluble sulfides, steaming the padded material, rinsing,and subsequently dye-' ing it in a bath containing a reduced indigoid oranthraquinone vat dye. These vat dyes may be reduced by any of the knownmethods but a caustic-soda-hydrosulflte reduction is preferred.

Inplace of padding and steaming, the pretreatmerit can be 'efiected byimmersing the wool in a bath containing one of the compounds mentionedabove and treating at elevated temperatures as more fully explainedbelow. Dyeings of indigoid and anthraquinone vat dyes on wool pretreatedby either of these methods are considerably stronger than when thepretreatment is omitted. The concentration of the pretreating agent inthe pad liquor is not critical; but the preferred range is about 2 170.3ounces per gallon. Padding may be carried out at any temperature,although temperatures of 140' to 160" F. insure better penetration ofthe wool. After padding, the impregnated material is steamed atatmospheric pressure, preferably for 3 minutes, and rinsed.

In the alternative method mentioned above, the wool is treated in theform of piece goods, skeins or raw stock, in a bath containing 3 to 5%,based on the weight of the material, clone of the compounds mentionedabove for 5 to 30 minutes at 160 to 212 F. The preferred method is atreatment for minutes at 200 F. While temperatures below 160 F. may beemployed, they cannot be considered commercially practical due to theproportionate increase in time necessary to obtain the desired effect.

solution of a' vat dye. Any normal procedure for the dyeing of woolissatisfactory, where precautions are taken to avoid excess alkalinitywhich has a deleterious eflect'on the wool.

Besides iormamidine sulflnic acid, other. suitablepretreating agents aresodium and zinc hydrosulflte, sodium, zinc and basic zinc formaldehydesulfoxylate', sodium. Potassium and zinc bisulflte, sodium and potassiumsulfide. It will be clear from these examples, and numerous others which-I have tried, that the agents suitable for this invention are compoundsof the type generally employed asvat-reducing agents, but characterizedfurther by'containing sulfur in the molecule. However, it should not beinferred that these agents have the function ofassisting merely in thereduction of the vat dye in the value for the continuous dyeing ofwoolen piece goods with vat colors, for example indigo. Thus, due to theincreased aflinity, it is possible by this invention to. obtain deepnavy shades on wool by dyeing for only 3 minutes in a bath containing 3ounces per gallon of reduced indigo, paste,

5 whereas when using conventional methods, it would be necessary to dyefor 10 minutes, then oxidize and dye for an additional 10 minutes in asecond bath, to obtain a similar depth of shade. Such a procedureobviously would not lend itself 49 to a continuous dyeing process.

' conventional methods. This shorter dyeing time A further advantage isthe fact that the increased aflinity of the wool permits the productionof light to dark shades with vat colors in a much shorter period of timethan when using furthermore reduces the possible deleterious effect ofalkalies, necessary for the reduction of vat dyes, on the wool fibers. I

A further advantage is the fact that wool pre- 5 treated as describedcan be readily dyed with those vat colors which normally have little orno afljinity for wool, for example Ponsol" Blue GD Double Paste (ColorIndex #1113).

Without limiting my invention to any particu- After pretreating byeither one of the described Procedure, the following examples are givensubsequent dyeing step, inasmuch as I have found to illustrate mypreferred mode of operation. Parts entioned are by weight.

Example 1 W001 felt is padded at 150 F. throu h an aqueous solutioncontaining 2% ounces per gallon of iormamidine sulflnic acid. The timeof immersion is approximately 3 seconds (operative range 1 to 10seconds) and the squeezing rolls are adjusted to permit the material toretain 100% of its weight of moisture. The impregnated material is thenrun directly into a steamer where it is steamed for 3 minutes (operativerange 1 to 5 minutes) at atmospheric pressure and then run through arinse box containing water of about 80 F. After squeezing to removeexcess moisture the steamed and rinsed felt is run through a vat con-'taining 3 ounces per gallon of reduced indigo, 20%

. stronger in shade than if untreated wool is dyed in an indigo vat ofthe same strength.

Example 2 W001 crepe is pretreated by padding through a solutioncontaining 2% ounces per gallon of sodium formaldehyde sulfoxylate,steaming and rinsing as described in Example 1. After dyeing with indigo20% paste as described in Example 1,

and oxidized by chemical means. Dyeings on pretreated material are atleast 50% stronger than dyeings on untreated crepe.

Example 6 W001 crepe is pretreated with formamidine sulilnic acid asdescribed in Example 1. After steam-,- ing and rinsing the material isdyed as described in Example 5, the color selected in this case beingPonsol Jade Green Double Paste (Color Index #1101) The dyeing isconsiderably stronger than that obtainable on untreated wool.

Example 7 Wool crepe is pretreated with formamldine sulflnic acid asdescribed in Example 1, and dyed as described in Example 5, the colorselected being Sulfanthrene" Blue 23D Paste (Color Index #1184). 7Pretreated material is dyed very much heavier than untreated wool.

Example 8 Wool crepe is pretreated with formamidine sulfinic acid asdescribed in Example 1 and dyed as described in Example 5, the colorselected being "Ponsol" Blue GD Double Paste (Color Index #1113). Thedyeing is very much stronger than that obtainable on untreated material.I

much heavier shades are obtained than if the pretreatment is omitted. 7

Example 3 W001 flannel is pretreated by padding through a solutioncontaining 2 ounces per ga'llonot sodium bisulfite, steaming andrinsing, and sub= sequently dyeing with indigo 20% paste as de-' scribedin Example 1. Much heavier shades are obtained than when thepretreatment is omitted.

Example 4 W001 skeins are pretreated by immersing for 15 minutes at 200F., at a volume of 40:1, in a bath containing 5% formamidine sulfinicacid, based on the weight ofthe material. After draining and rinsing,the skeins are dyed for 10 minutes in a bath containing one ounce pergallon of reduced indigo 20% paste. After oxidizing, the pretreatedskeins are much heavier in shade than material not thus pretreated.

Equally satisfactory results are obtained by the substitution of 5%sodium sulfide, based on the weight. of the material, for theformamidine sulfinic acid.

- Example 5 W001 crepe is pretreated by padding through a solutioncontaining 2 ounces per gallon of formamidine sulfinic acid, steamingand rinsing as described in Example 1. It is then passed through a bath,for 2 minutes at 125 F., containing one ounce per gallon of reduced"Ponsol Red BN Double Paste (Color Index #1162). The vet dye was reducedwith hydrosulfite and caustic soda, as commonly employed in the dyeingof cotton. To present an undue deleterious: action of the alkali on thewool, however, only oi the normal amount of caustic soda was used forre= duction. After passage through the dye bath, the

- sulfinic acid as described in Example 1.

Till

wool crepe is squeezed to remove excess moisture. 93d

Example 9 W001 crepe is pretreated with fordamidine suliinic acid asdescribed in Example 1 and dyed as described in Example 5, the colorselected being "Ponsol" Violet AR Paste (Color Index #1135).

The dyeing is very much stronger than that obtainable on untreatedmaterial.

Example 10 Wool crepe is pretreated with sodium form- .aldehydesulfoxylate as described in Example 2 and dyed as described'in Example5, the color selected being Ponsol" Blue Green FFB Double Paste (ColorIndex #1173). The dyeing is very much stronger than if the pretreatmentis omitted.

' Example 11 Wool crepe is pretreated with sodium formaldehydesulfoxylate as described in Example 2 and dyed as described in Example5, the color selectel in this case being Ponsol Golden Orange RRT Paste(Color Index #1097). The dyeing is very much stronger than is obtainableon untreated material.

Example 12 Wool crepe is pretreated with formamidine After steaming andrinsing, the material is padded at 140 F. through a solutioncontaining 2ounces per gallonof the leuco ester of "Ponsol Jade Green (Color Index#110l) and one ounce per gallon sodium nitrite, The padded material isthen developed at '70 to F. for 3 minutes in a 2% solution of sulfuricacid, rinsed and soaped. Much heavier dyelngs are obtained on pretreatedwool crepe than on untreated material.

Equally satisfactory results are obtainable if the leuco ester of thevat dye is applied by dyeing in a heel: or jig'instead of by padding.

It will be understood that my invention is susceptible of wide variationin details, within the skill of those versed with this art, withoutdeparting from the spirit of this invention.

I claim:

1. In a process of dyeing wool fiber with vat of the agent in the bathbeing insuflicient to reduce the wool to a rubber-like condition;heating the impregnated fiber, and then subjecting the same to vatdyeing in a bath containing the chosen vat color, alkaline agents andreducing agents.

2. A process as in claim 1, the heating being efiected simultaneouslywith the impregnation, by using a hot impregnation bath, at atemperature between 160 and 212 F.

3. A process as in claim 1, the heating being eflected by subjecting thefiber to steam ageing at atmospheric pressure, subsequent to treatmentwith the impregnation bath.

4. A process of dyeing wool fiber, which comprises pretreating the samein an aqueous bath containing a sulfur-containing vat-reducing agent inquantity not exceeding 3 ounces per gallon, but no added alkali and nocoloring matter, and heating the treated fiber; then rinsing the fiberand dyeing the same from an alkaline aqueous bath containing a reducedvat dye of the group consisting of anthraquinone vat dyes and indigoidvat dyes, "the time of dyeing not exceeding 3 minutes; and finallysubjecting the dyediiber to an oxidation treatment, to reoxidize the dyeon the fiber.

5. A process for the continuous dyeing of wool with indigo, whichconsists in the impregnation of the wool with an aqueous solution offormamidine sulfinic acid at a concentration of from 2 to 3 ounces pergallon steaming the fiber and rinsing; the time of impregnation notexceeding 10 seconds, and the time of steaming not exceeding 5 minutes,then immersing the wool in an aqueous allgaline bath containing reducedindigo, removing the fiber from the bath and oxidizing the color on thefiber.

GUSTAVE THEODORE HUG.

